Web applications oftentimes utilizes various JavaScript objects or models (or other objects or models in other interpreted programming languages) that reside in, for example, browser memory. Web developers may need to define what types of data may be entered into a model for at least some of the fields in the model. Such data may comprise a varieties of types entered in a variety of different manners by different users. Some of the data may thus include undesired data or even invalid data. A complex web-hosted application may include extremely large amount of data and a large number of models. Some of the data or models may interact with each other. Some of the earlier entered data or earlier executed models may even affect subsequently entered data or subsequently executed models. Including undesired data or even invalid data in various models may thus be detrimental to the user experience and also to the usability or even viability of the website hosting the software applications.